Wildfire seasonality and land use: when do wildfires prefer to burn?

Because of the increasing anthropogenic fire activity, understanding the role of land-use in shaping wildfire regimes has become a major concern. In the last decade, an increasing number of studies have been carried out on the relationship between land-use and wildfire patterns, in order to identify land-use types where fire behaves selectively, showing a marked preference (or avoidance) in terms of fire incidence. By contrast, the temporal aspects of the relationship between landuse types and wildfire occurrence have received far less attention. The aim of this paper is, thus, to analyze the temporal patterns of fire occurrence in Sardinia (Italy) during the period 2000–2006 to identify land-use types where wildfires occur earlier or later than expected from a random null model. The study highlighted a close relationship between the timing of fire occurrence and land-cover that is primarily governed by two complementary processes: climatic factors that act indirectly on the timing of wildfires determining the spatial distribution of land-use types, and human population and human pressure that directly influence fire ignition. From a practical viewpoint, understanding the temporal trends of wildfires within the different land-use classes can be an effective decision-support tool for fire agencies in managing fire risk and for producing provisional models of fire behavior under changing climatic scenarios and evolving landscapes.     

Prediction of syngas quality for two-stage gasification of selected waste feedstocks

This paper compares the syngas produced from methane with the syngas obtained from the gasification, in a two-stage reactor, of various waste feedstocks. The syngas composition and the gasification conditions were simulated using a simple thermodynamic model. The waste feedstocks considered are: landfill gas, waste oil, municipal solid waste (MSW) typical of a low-income country, the same MSW blended with landfill gas, refuse derived fuel (RDF) made from the same MSW, the same RDF blended with waste oil and a MSW typical of a high-income country. Energy content, the sum of H2 and CO gas percentages, and the ratio of H2 to CO are considered as measures of syngas quality. The simulation shows that landfill gas gives the best results in terms of both H2+CO and H2/CO, and that the MSW of low-income countries can be expected to provide inferior syngas on all three quality measures. Co-gasification of the MSW from low-income countries with landfill gas, and the mixture of waste oil with RDF from low-income MSW are considered as options to improve gas quality.     

Geomorphological evolution and environmental reclamation of Fusaro Lagoon (Campania Province, southern Italy)

Analysis of morphological, geological and environmental characteristics of the Fusaro Lagoon has shown the present degraded condition of the lagoon and the perilagoon area. The lagoon developed during the mid-Holocene within a wide marine bay confined between the coastal volcanic structures of Mt. Cuma to the north and Torregaveta to the south in the western part of the Phlegrean Fields. Subsequently, the bay was gradually filled with pyroclastic materials from phlegrean eruptive vents and sediments carried by the rivers Volturno and Clanis, thus, creating an open lagoon. It then evolved into a partially closed lagoon due to the formation of a continuous littoral spit during the late Holocene, probably wider than the present-day one and surrounded by marshlands. Finally, the total closure of the lagoon took place in the Graeco-Roman period, following the stabilization of the dune ridge, and it assumed a shape similar to present-day one only towards the end of the 18th century.Between the Roman period and 1941, three lagoon channels were opened in order to avoid the frequent environmental crises which continue to affect, although for different reasons, this salt-water basin. The basin has been exploited for more than 2000 years not only for mollusc culture and pisciculture, but also for the maceration of hemp and flax. In the 1980s, in order to reduce the effects of the environmental crises, dredging of the lagoon bottom has been carried out, altering the hydrogeological equilibrium and that of the ecosystem. Over the past 30 years, the supply of raw sewage of domestic, agricultural and industrial origin has ensured the presence of a high concentration of pollutants, including heavy metals.On the basis of the data obtained and in order to restore this sensitive transitional environment, eco-compatible interventions are proposed which aim at morphological and hydrologic resettlement, abatement of pollutants on the bottom of the basin, reintroduction of endemic molluscs, together with monitoring the quality of sediments and both sea-lagoon waters and groundwater.     

Solidification/stabilisation of arsenic bearing fly ash from the metallurgical industry. Immobilisation mechanism of arsenic

When a fly ash waste material from a copper refining process containing large amounts of As2O3 is solidified using cement and lime, the arsenic concentration in the leachate can be lowered to ca. 5 mg/l in a saturated solution of Ca(OH)2. It is shown that the decrease of the concentration in the leachate, mainly of As(III), is due to the formation of insoluble CaHAsO3 in the leachate in the presence of Ca(OH)2. This method is compared with a method whereby use is made of oxidation of the waste before solidification to oxidise As(III) to As(V) using H2O2. The arsenic concentration in the leachate of the extraction test of an oxidised S/S sample was lowered to ca. 0.5 mg/l, a factor of 10 below the one for a non-oxidised sample. It is shown that the decrease of the concentration in the leachate mainly of As(V) is due to the formation of insoluble Ca3(AsO4)2 in the presence of Ca(OH)2. Extensive use was made of the speciation program MINTEQA2, to clarify the immobilisation of arsenic.     

Electrochemical remediation of copper (II) from an industrial effluent Part II: three-dimensional foam electrodes

A batch recycle removal of copper ions from an industrial effluent by means of copper foam cathodes was tested. A constant current of 750 A was applied to the cell in order to perform the reduction. Copper depletion was investigated at different solution flow rates and a removal greater than 98% was obtained with a flow rate of 1000 l/h. The influence of initial metal concentration on copper deposition and current efficiency is also discussed.     

Improving eco-efficiency in the steel industry: The ArcelorMittal Gent case

In addition to CO₂ released by the combustion of fossil fuel and leading to climate change, large steelworks emit pollutants that have other environmental impacts. ArcelorMittal Gent, an integrated steelwork producing ca. 5 × 10⁶ tons of steel per year, not only decreased its specific energy consumption and CO₂-emissions, but also reduced the environmental impact of its other emissions. This is illustrated by means of the evolution of 6 partial eco-efficiency indicators for the impact categories acidification, photo-oxidant formation, human toxicity, freshwater aquatic ecotoxicity, eutrophication and water use. The partial eco-efficiency indicators are eco-intensities, defined as the environmental impact in the respective impact category, divided by the amount of liquid steel produced. In the period 1995 – 2005 these indicators decreased by 45, 4, 52, 9, 11 and 33% respectively, whereas the steel production increased by 17%. The net impact of discharges of wastewater is negligible for human toxicity and is negative (concentrations lower than in the canal water used) for freshwater aquatic toxicity and eutrophication. For acidification, human toxicity (only emissions to air) and water use, the decoupling between environmental impact and production was absolute; for photo-oxidant formation, freshwater aquatic ecotoxicity (only emissions to air) and eutrophication, it was relative.     

Optimising energy recovery and use of chemicals,resources and materials in modern waste-to-energy plants

Due to ongoing developments in the EU waste policy, Waste-to-Energy (WtE) plants are to be optimized beyond current acceptance levels. In this paper, a non-exhaustive overview of advanced technical improvements is presented and illustrated with facts and figures from state-of-the-art combustion plants for municipal solid waste (MSW). Some of the data included originate from regular WtE plant operation – before and after optimisation – as well as from defined plant-scale research. Aspects of energy efficiency and (re-)use of chemicals, resources and materials are discussed and support, in light of best available techniques (BAT), the idea that WtE plant performance still can be improved significantly, without direct need for expensive techniques, tools or re-design. In first instance, diagnostic skills and a thorough understanding of processes and operations allow for reclaiming the silent optimisation potential.     

Carbonation of MSWI-bottom ash to decrease heavy metal leaching, in view of recycling

The 0.1-2 mm fraction of a MSWI-bottom ash cannot be used as granular construction material because leaching of Cu exceeds Flemish limit values. In addition, leaching of Ba, Mo and Sb exceeds informal limit values. Leaching characteristics thus need to be improved. Carbonation was the chosen treatment method and this was performed by placing samples in a CO2 chamber. The CO2 percentage and the temperature of the chamber atmosphere, as well as the initial humidity of the samples, were varied to optimize carbonation parameters. Metal leaching was tested with the EN 12457 extraction test. Carbonation decreased Cu leaching from 3.3 to 1.0 mg/kg, but not yet to below the official limit value of 0.5 mg/kg. Leaching of Mo and Sb remained fairly constant or even increased after carbonation, but their limit values are only informal. Ba leaching decreased to below the informal limit value. Carbonation also caused Cr leaching to increase, in some cases to above the official limit value. Of the tested parameters, a CO2 percentage of 10% and a carbonation temperature of 50 degrees C in the atmosphere, together with ash humidity between 13% and 25% appeared to give the best leaching results. The main carbonation reactions took place within the first 24 h.     

Canopy profiles of photosynthetic parameters under elevated CO2 and N fertilization in a poplar plantation

A poplar plantation has been exposed to an elevated CO2 concentration for 5 years using the free air CO2 enrichment (FACE) technique. Even after such a long period of exposure, leaves of Populus x euramericana have not shown clear signs of photosynthetic acclimation. Only at the end of the growing season for shade leaves was a decrease of maximum velocity of carboxylation (Vcmax) observed. Maximum electron transport rate (Jmax) was increased by FACE treatment in July. Assimilation rates at CO2 partial pressure of 400 (A400) and 600 (A600) micromol mol(-1) were not significantly different under FACE treatment. Most notably FACE significantly decreased stomatal conductance (g(s)) both on upper and lower canopy leaves. N fertilization increased N content in the leaves on mass basis (Nm) and specific leaf area (SLA) in both CO2 treatments but did not influence the photosynthetic parameters. These data show that in poplar plantations the long-term effects of elevated CO2 on photosynthesis do not differ considerably from the short-term ones even with N deposition.